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RE: Where does RDF fit in with XQuery?

From: Anthony Finkelstein <a.finkelstein@cs.ucl.ac.uk>
Date: Fri, 22 Jun 2001 16:52:46 +0100
Message-Id: <v0421010ab759198a6e52@[128.16.64.188]>
To: Gary Zakon <gzakon@rcn.com>, Libby Miller <Libby.Miller@bristol.ac.uk>, www-rdf-interest <www-rdf-interest@w3.org>, www-ql <www-ql@w3.org>
If you want to assert relationships  [and check] between XML document 
types you might wish to use our approach specifically designed for 
this purpose ... like our assertion language and checker 
http://www.xlinkit.com

Anthony



At 11:44 am -0400 22/6/01, Gary Zakon wrote:
>Libby,
>
>Thank you - this does help.  I do understand why you would want to query RDF
>using an RDF oriented query language vs. XQuery.  However, I still have a
>question that perhaps I can formulate better now:
>
>If RDF provides meta-information regarding the relationship between two
>different XML document types can I use this meta-information to help me
>formulate an XQuery that extracts information from the two related document
>types?  In other words, do I use RDF to assert relationships between XML
>document types that cannot be asserted using XML Schema?  My understanding
>is that XML Schema provides the meta-information for a single XML document
>type and cannot provide meta-information describing the relationship between
>XML document types.  RDF is for this purpose, correct?
>
>Does RDF meta-information ever include instance data from the XML documents
>being described?  Which use is more prevalent - providing meta-information
>regarding XML document types or providing meta-information regarding XML
>document instances?  Does this question make sense?
>
>Thanks again,
>
>Gary
>-----Original Message-----
>From: www-ql-request@w3.org [mailto:www-ql-request@w3.org]On Behalf Of
>Libby Miller
>Sent: Thursday, June 21, 2001 9:21 PM
>To: Gary Zakon
>Cc: www-ql; christop@ics.forth.gr
>Subject: Re: Where does RDF fit in with XQuery?
>
>
>
>hi Gary
>
>I think there are a few people working on the relationship between
>Xquery and RDf query languages at the moment, among them Jonathan Robie
>(XQuery) and Vassilis Christophides and others (RQL). I've been helping
>Jonathan out with the RDF side of things.
>
>Basically, because there are many different ways of serializing any
>given RDF description of, say, a document in XML (see examples in the
>RDF model and syntax - http://www.w3.org/TR/REC-rdf-syntax/), XQuery
>isn't the easiest way to query RDF. A more straightforward way is to
>query the underlying model, which is based on triples, regardless of the
>exact syntax. This is what I've done with my prototype RDF query
>language Squish, and what the RQL people have done in a rather more
>finished way.
>
>So it would be nice to query xml documents and the meta-information
>about them in one format, but this looks difficult unless the RDF is in
>some canonical format (there isn't one for RDF at least at the moment).
>
>As regards schemas, I would think that XMLSchema would be more useful
>for guidence on the sort of XQueries against XML documents that are
>likely to be sucessful. RDF Schemas can perhaps help you with RDF
>queries.
>
>does that help at all?
>
>RQL:
>http://139.91.183.30:9090/RDF/RQL/
>
>Squish:
>http://swordfish.rdfweb.org/rdfquery/
>
>RQL/Squish comparison demo
>http://swordfish.rdfweb.org/discovery/2001/06/squishtests/
>
>Libby
>
>
>On Thu, 21 Jun 2001, Gary Zakon wrote:
>
> > Hi,
> >
> > I'm struggling a bit with understanding the role of RDF and its
>relationship
> > to XML Schema and now XQuery.  Any help anyone can offer to clarify things
>a
> > bit is much appreciated.
> >
> > What role (if any) does RDF play with respect to XQuery?  XQuery allows me
> > to query across multiple XML documents.  If those documents are described
> > using RDF does that help me formulate my queries in any way?  For example,
> > RDF can inform me of the relationships between different XML documents.
>Or
> > is the XML Schema for those documents more relevant?  Or are they both
> > relevant?
> >
> > Thanks,
> >
> > Gary
> >
> >

___________________________________________________________________________

Anthony Finkelstein (Prof.) 	| TEL: +44 (0)20 7679 7293 (Direct Dial)
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Received on Friday, 22 June 2001 11:54:00 GMT

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